PARIS — The indoor use of electronic cigarettes should be banned and sales to minors should be prohibited, the World Health Organization said.

Manufacturers also should be prohibited from claiming that the devices can help people quit smoking until they provide convincing evidence, the Geneva-based United Nations agency said in a report Tuesday. The recommendations will be discussed in October at a meeting in Moscow of the WHO’s Framework Convention on Tobacco Control.

E-cigarettes “are the subject of a public health dispute among bona fide tobacco-control advocates that has become more divisive as their use has increased,” according to the report.

The report is likely to fuel the debate over how e-cigarettes should be regulated and whether they’re safer than traditional cigarettes.

The American Heart Association Monday said the devices are worth trying as a last option for smokers seeking to quit.

Adult smokers who switch totally to e-cigarettes that are well regulated will probably have reduced exposure to toxic substances, though the amount of risk reduction is unknown, the WHO said.

E-cigarettes have ballooned from one Chinese manufacturer in 2005 to a $3 billion industry with more than 460 brands last year, according to WHO. The U.S. and European Union are the biggest markets.

The WHO is concerned that the tobacco industry is taking a greater share of the e-cigarette market, “pretending to be part of the solution to the health disaster they have created,” Douglas Bettcher, director of the WHO’s non-communicable diseases department, said.

The agency is concerned about the so-called gateway effect of e-cigarettes, in which rather than being used to help people stop smoking, they may be an entry point for non-smokers.

Advocates of e-cigarettes as a way to quit said the WHO’s recommendations will do more harm than good.

Earlier this year, 53 nicotine scientists and health researchers who sent a letter to WHO Director-General Margaret Chan this year urging that e-cigarettes not be regulated in the same way as tobacco.